Estrogen therapy (ET) is used to treat the symptoms of menopause. It reduces or stops the short-term changes of menopause such as hot flashes, disturbed sleep, and vaginal dryness. Estrogen therapy can prevent osteoporosis, a consequence of lowered estrogen levels. Vaginal estrogen therapy products help with vaginal dryness, more severe vaginal changes, and bladder effects but, since very little vaginal estrogen enters the circulation, it may not help with hot flashes or prevent osteoporosis.

The use of unopposed estrogen therapy (ET alone) is associated with an increase in the risk of endometrial cancer (cancer of the lining of the uterus). However, by taking the hormone progestogen along with estrogen, the risk of endometrial cancer is reduced substantially. Progestogen protects the uterus by keeping the lining of the wall of the uterus (endometrium) from thickening (an effect caused by estrogen). The combination therapy of estrogen plus progestogen -- hormone therapy (HT) – was in common use. Data in 2002 from the Women's Health Initiative (WHI), however, showed that hormone therapy may be associated with certain health risks. Specifically, postmenopausal women taking the combination estrogen-progestin (Prempro) were at a small but definite increased risk for developing heart disease, breast cancer, stroke, and blood clots when compared with women not taking hormone therapy. The risks for women taking estrogen therapy alone without progesterone included an increased risk for stroke and blood clots.

Newer data has suggested that estrogen may decrease risk for heart disease when taken early rather than later in the postmenopausal period, but the overall risks and benefits of hormone therapy are not fully understood.

While long-term hormone therapy is no longer recommended, hormone therapy may still play a role in the treatment of severe menopausal symptoms, particularly in younger women. The healthcare provider can help to weigh the risks and benefits of estrogen therapy or hormone therapy on a case-by-case basis.